measure how far out is the barrel portion of the plunger.
18mm (.71") is the recommended limit
22mm (.87") is the absolute limit

My plunger was out about 0.63".   I'm going to take the chain off and measure it next.  I just bought the bike, with the knocking sound.  It was cheap and I figured I could sort it.  I don't hear it at idle except occasionally, then as soon as I apply throttle it comes in and then at high revs it either goes away or gets drowned out by standard engine noise, or just goes so fast it blends in with what I consider normal engine noise.  

I reckon I'll take the motor out now and take off the valve cover off.  I note that someone has already had the valve cover off (again only 5700 miles on it) as there's red RTV under it.  Should be easier to reach the valves for checking clearance too.

So my next question, are the exhaust valves supposed to be this white?

SinglesGoinSteady wrote on 02/20/12 at 10:26:35:

They often look thst white as the bike runs ridiculously lean from the factory. As for the valve cover, the previous owner maybe had the scheduled re-torqueing of the head nuts and bolts done, which requires to remove the head cover.

Yea,, Im thinkin youre about to make a big project out of a simple thing,Id sure start with adjusting the valves, & do consider the Verslagen mod on the tensioner, its a $$$ saver,

pic of plunger = 1.2"

Ya, that's a brilliant, slick little mod Verslagen.